This invention relates to an electromagnetic wave isolation apparatus that is suitable to use in household multi-outlets.
Nowadays, due to the wide usage of electrical appliances and personal computers in the office or home, use of multi-outlets is indispensable for supplying them with electricity. Some of multi-outlets have many functions such as electrical surge suppression, over current protection, and noise removal function for the safety of the user and electrical appliances, as well as its original power distribution function.
However, in most homes and offices, a significant amount of electromagnetic waves are generated by the use of electrical appliances, for example, refrigerators and the like employing electric motors, and television sets and computer monitors employing high voltage devices.
However, there have been few measures for isolating the electromagnetic waves generated in homes or offices, although electromagnetic waves are known to be harmful to the human body.
As is well known in the art, when electricity flows, electrical and magnetic fields are simultaneously generated around a conductor. A wave motion occurred by the periodic change between the electrical field and magnetic field is referred to as the electromagnetic wave. The electrical field and magnetic field are different from each other in property but they are combined with each other. The electromagnetic wave is generated at any location where electricity flows and thus the electromagnetic wave is inevitably generated in every electrical apparatus.
Further, the electrical field is generated in proportion to the amplitude of voltage, and the magnetic field in proportion to the intensity of electric current. The electrical field may be quite isolated by a material having high conductivity. However, only a ferromagnetic substance or alloys block the magnetic field and it is thus very difficult to isolate the magnetic field.
According to a survey, an amount of electromagnetic waves are found in the home and office space. For example, in a living room of about the size of 33 m2 (where a television set, electric fan, and fluorescence lamps are used) the electrical field intensity is measured to be about 18.6 V/m, and in an office of about 66 m2 (where computers, copying machines, fluorescence lamps, air conditioner, facsimile machine, printer, hot and chilled water dispenser, and a small size refrigerator are located) the electrical field intensity is about 19.1 V/m.
In addition, the amount of electromagnetic wave emission is measured in about 146.8 V/m at a distance of 30 centimeters from a computer set, about 193.1 V/m at a distance of 30 centimeters from a television set, about 193.2 V/m at a distance of 30 centimeters from a refrigerator (230 liters), and about 133.1 V/m at a distance of 30 centimeters from an air conditioner (66 m2 capacity).
Such an electromagnetic wave has been known to increase the temperature of cells of human tissue due to its thermal effect, thus to weaken the immunological function of the human body. The National Cancer Institute has advised that the electromagnetic wave may induce cancer.
Accordingly, with the recent increase for concern about the harmfulness of electromagnetic waves, a strong demand exists for a device capable of isolating and removing the electromagnetic wave occurring in the home and office.
Therefore, it is an object of this invention to provide an electromagnetic wave isolation apparatus that is incorporated in a multi-outlet used in the home or office.
It is further object of this invention to provide an electromagnetic wave isolation apparatus which may isolate the electromagnetic wave occurring in the home or office in a simple and easy manner.
According to the invention, there is provided an electromagnetic wave isolation apparatus for use in multi-outlets, which apparatus comprises an electromagnetic wave detecting circuit for sensing induced electromagnetic waves generated in the home or office and generating an output signal responsive to a predetermined level of the induced electromagnetic wave; an electromagnetic wave isolation circuit in response to the output signal of the detecting circuit to generate an output signal for driving a lamp which indicates the presence of electromagnetic waves and subsequently for driving a switch which enables one of the AC output lines to be connected with the circuitry ground of the multi-outlet; a switching circuit for activating a second switch provided in each of the AC output lines in response to the output signal of the isolation circuit; and a resistor connected between the circuitry ground and the ground terminal of the power cord of the multi-outlet.
Preferably, the electromagnetic wave isolation circuit of this invention includes a buzzer for audibly indicating the presence of electromagnetic waves, and the lamp is a light emitting diode.
In one embodiment of this invention, the above switching circuit includes a relay with its switch interposed between each of the AC output line and the circuitry ground of the multi-outlet. The switching circuit further includes a transistor driving circuit for activating each of the relays.
Further, a ground pin contact of each receptacle provided in the multi-outlet is commonly connected with the circuitry ground terminal of the electromagnetic wave isolation apparatus through a thermistor.